This invention refers to a bringer gripper for the weft yarn in textile looms without shuttles.
More in detail, this invention refers to a gripper for the feeding of weft yarns to the grippers of looms without shuttles, suitable for processing multiple weft yarns at the same time, by presenting them at the warp inlet to the taker gripper, in an order controlled and predetermined in the delivery phase of the weft yarns.
This delivery occurs within a limited time and space interval, when the gripper moves into and pulls back from the cavity of the bringer gripper which has carried the weft yarns halfway into the warp inlet, picks up the weft yarns and completes their run to the opposite side.
To describe the technical problem faced by this invention in greater detail, along with the peculiar difficulties and requirements of the gripper-type looms, reference will now be made to the process of presenting the weft yarns in these looms, as shown in a simplified manner in FIGS. 1A and 1B.
FIG. 1A shows the fabric 1 already produced on the right side, and the warp inlet already opened in the two planes 2 and 3 by the motion of the heads, not shown in the figure for simplicity. In the warp inlet, at each of its openings and with the appropriate synchronization, one or more wefts must be inserted depending on the patterns of the fabric to be produced, and these wefts, or weft yarns, are delivered to a bringer gripper 4 moved inside the warp inlet by a lance of a semi-rigid ribbon 5, which wraps up and unwraps with an alternating rectilinear motion in the sense of the double arrow 6, as a result of the alternating rotary motion in the sense of the arrow 7 of the lateral driving wheels 8. In the most widely used looms the inserting of the weft yarn is done by a pair of grippers cooperating with each other: the bringer gripper and the taker gripper. They move by starting off from the two sides of the fabric and meet at the halfway line, where the bringer gripper 4, after picking up the yarn from the presenting device and completing its run over half the height of the fabric, delivers it to the taker gripper coming from the opposite side. After picking up the yarn, the taker gripper pulls back and completes its run over the remaining half of the fabric""s height.
For further details on the taker grippers reference can be made to European patents Nos. 572.025 and 576.074, as well as to European patent application No. 95202072.5 by the same applicant. As a general principle, the bringer gripper is designed with a hollow front end where the weft yarns are presented to the taker gripper, which is in turn shaped like a hook capable, while advancing, of dipping into the hollow end of the bringer gripper and, while retracting, of gripping and carrying along these yarns, so as to complete their insertion into the warp pick.
After thus being introduced into the warp inlet, the weft yarn, or simply yarn, is inserted into the fabric by the motion of the reed, not shown in the figure for simplicity. In its alternating rectilinear motion the body of the bringer gripper 4 moves along the dotted horizontal trajectory 9.
The operation of presenting the weft yarn to the bringer gripper 4 occurs by presenting some rods 11 which receive their weft yarn 12 from their respective upstream reel. These presenting rods 11 are capable of moving between two places, an upper resting place and a lower delivering place for the respective weft yarn to the bringer gripper 4.
For the weft yarns"" presenting devices, reference can be made to Italian patent applications Nos. MI97/A01821 and MI97/A01822 by the same applicant.
As known from the state of the art, the weft yarn is presented to the bringer gripper at an appropriate angle with respect to its trajectory 9. More precisely, the various weft yarns are presented according to a certain range of directions lying in a plane, always at a sharper or softer angle with respect to the direction 9 of the forward motion of the bringer gripper 4. In its forward motion the bringer gripper, while on its way into the warp inlet, successively crosses the weft yarns"" various directions available, first those at a sharper and then those at a softer angle.
It must in fact be kept in mind that the bringer gripper is at the moment produced in a shape fitting the specific requirement of gripping only the yarns it encounters at a sharp angle, and of absolutely failing to grip the yarns it encounters at essentially less than sharp angles. This requirement conforms to the need that in case the warp inlet is not perfectly open and the warp yarn is not fully raised or lowered, the bringer gripper 4 must not grip and tear it, but only deflect it from its path, by raising or lowering it to the necessary place.
FIG. 1B gives an overall view of the situation after the yarn is gripped by the gripper 4 and after it has moved forward in the direction 9 toward the open warp inlet. Downstream of the yarn presenting and gripping place, a cutting organ 14, conventionally pictured here as a scissors, intercepts the weft section between the moving gripper 4 and the top of the warp inlet and cuts it, so that the weft yarn moved into the open warp inlet is that unrolled from its upstream reel and does not affect the yarn on the part of the fabric 1 which has already been produced. In fact, FIG. 1A shows the scissors in an open and FIG. 1B in a closed position, after cutting the yarn 12.
The technical problem of presenting the weft yarn turns more complex when two or more wefts are to be conveyed to the warp inlet simultaneously, by feeding them to the bringer gripper and delivering them from there to the taker gripper. These wefts may in fact turn out to be highly different in their dimensional characteristics and so on, or be presented at different stretching values or free lengths, so as to be consequently gripped with greater or lesser efficiency by the bringer grippers and taker grippers.
In consideration of the fact that the wefts are gripped and held firm by V-type notches and/or elastic organs, it proves to be most important for a good fabricating result that the introduction of the yarn hardest to retain in the bringer gripper occur in a controlled sequence between the yarns 12, as in its delivery to the taker gripper. It is generally preferable that the delivery of the most troublesome yarn to the taker gripper should take place first. If one keeps in mind, again as a general principle, that the taker grippers are shaped like hooks of a very sharp V-type form, it is preferable that the yarn most troublesome to hold enter the V-shaped recess first, and that the less troublesome yarn enter it thereafter.
The scope of this invention is to produce an advanced weft feeding device and processing system in gripper-operated looms, particularly in case of a simultaneous feeding of multiple wefts. The technical problem of enhancing the process of feeding the wefts to the textile process and the device governing this phase of the process in gripper-operated looms therefore essentially rests on the requirements of making two or more wefts available in differentiated and defined places in the bringer grippers, so as to present them in a pre-established sequence to the taker gripper, and that the latter may be able to pick them up in this sequence, as well as to control the motions of moving the mentioned wefts into the bringer gripper.
This invention consists of a device and a feeding process of the weft yarns into looms without shuttles, particularly suited to the simultaneous feeding of a multiple number of weft yarns to the textile process.
A bringer gripper for Jooms without shuttles is disclosed. The bringer gripper has a boxy parellelpiped hollow shape, built from a lower U-shaped bar and upper cover. The upper cover is fitted with a notch in which the weft yarn or weft is placed by the feeding reel, and in combination with a gripping organ is capable of capturing the weft on the part turned toward the fabric to present the weft to the taker gripper. The notch is shaped with a multiple number of throats of different axial lengths, so as to basically offset the weft yarns. The weft yarns come to rest at the bottom of each of the multiple throats in the direction of the axial motion of the gripper.
A method of presenting the weft yarns or wefts to a taker gripper of a loom without a shuttle equipped with a double gripper, and in particular for the double feeding of one or more wefts into the inlet of the warp, is disclosed. The wefts are arranged in the bringer gripper in a manner essentially offset in the direction of the axial motion of the grippers, and the wefts are presented to the taker gripper in the order of the offset arrangement. The order of presenting the wefts to the taker gripper is determined by the insertion of the wefts into the bringer gripper by placing them into a multiple number of throats of different axial lengths.
A platelet fitted with a projection having a rising profile on which the weft yarn is deflected into the bringer gripper is provided. This platelet is linked to the stationary structure of the machine and assists the introduction of the weft yarn into the bringer gripper. This linkage is adjustable in the direction of motion of the bringer gripper.